SRD:Axiomatic

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Axiomatic: An axiomatic weapon is lawfully aligned and infused with the power of law. It makes the weapon law-aligned and thus bypasses the corresponding damage reduction. It deals an extra 2d6 points of damage against all of chaotic alignment. It bestows one negative level on any chaotic creature attempting to wield it. The negative level remains as long as the weapon is in hand and disappears when the weapon is no longer wielded. This negative level never results in actual level loss, but it cannot be overcome in any way (including restoration spells) while the weapon is wielded. Bows, crossbows, and slings so crafted bestow the lawful power upon their ammunition.